Students form a conjecture about the ratio of two areas in a quadrilateral, and use Sketchpad to search for a proof. In the process they verify or disprove their results for two different kinds of quadrilaterals. The link to the activity itself is to a zip file that contains both the activity in pdf format and the corresponding sketch.

This material is based upon work supported by the
National Science Foundation under Grant DUE-0226284.
Any opinions, findings, and conclusions or recommendations
expressed in this material are those of the author(s)
and do not necessarily reflect the views of the
National Science Foundation.